platinum

Chemistry. a heavy, grayish-white, highly malleable and ductile metallic element, resistant to most chemicals, practically unoxidizable except in the presence of bases, and fusible only at extremely high temperatures: used for making chemical and scientific apparatus, as a catalyst in the oxidation of ammonia to nitric acid, and in jewelry. Symbol: Pt; atomic weight: 195.09; atomic number: 78; specific gravity: 21.5 at 20°C.

2.

a light, metallic gray with very slight bluish tinge when compared with silver.

adjective

3.

made of platinum.

4.

(of a record, CD, or cassette) having sold a minimum of one million copies.

metallic element, 1812, Modern Latin, from Spanish platina "platinum," diminutive of plata "silver," from Old French plate or Old Provençal plata "sheet of metal" (see plate (n.)). The metal looks like silver, and the Spaniards at first thought it an inferior sort of silver, hence the name platina. It was first obtained from Spanish colonies in Mexico and Colombia, brought to Europe in 1735, and identified as an element 1741. Taken into English as platina (c.1750), it took its modern form (with element ending -ium) in 1812, at the time the names of elements were being regularized. As a shade of blond hair, attested from 1931. As a designation for a recording that has sold at least one million copies, it is attested from 1971.

platinum plat·i·num (plāt'n-əm)n.Symbol Pt A ductile malleable metallic element usually occurring mixed with other metals such as iridium, osmium, or nickel and used as a catalyst and in dentistry. Atomic number 78; atomic weight 195.08; melting point 1,768°C; boiling point 3,825°C; specific gravity 21.45; valence 2, 3, 4.

(plāt'n-əm) Symbol PtA soft, ductile, malleable, silver-white metallic element that usually occurs with osmium, iridium, palladium, or nickel. It has a high melting point and does not corrode in air. Platinum is used as a catalyst and in making jewelry, electrical contacts, and dental crowns. Atomic number 78; atomic weight 195.08; melting point 1,772°C; boiling point 3,827°C; specific gravity 21.45; valence 2, 3, 4. See Periodic Table.